Typical wireless communication channels, which change randomly, are featured with frequency selectivity and time variation. The random change of the communication channels should be taken into consideration when designing wireless communication systems, and this randomness can be utilized by superior designs to improve the system performance and capability. One important thought is to change a transmission rate by adjusting an MCS dynamically according to real-time channel quality. The technology of dynamic MCS selection, which is a key technology for 3G, 4G and even future wideband wireless communications, has been broadly applied in the field of 3G and 4G is wideband wireless communications such as Long Term Evolution (LTE), Worldwide Interoperability for Microwave Access (WiMax), and etc.
The technology of dynamic MCS selection requires a transmitter (e.g. a base station) to have real-time channel quality information which can be obtained after being fed back by a receiver (e.g. User Equipment (UE)).
Since there is a certain time delay from the moment when a receiver estimates a channel and selects an MCS to the moment when a transmitter uses a fed-back MCS, the channel conditions at the moment when the transmitter uses the fed-back MCS are different from the channel conditions at the moment when the receiver selects the MCS. The difference is caused by channel changes and interference, therefore, in the existing technical conditions, the MCS fed back by the receiver is not applicable to the channel conditions at the moment when the transmitter performs transmission.